The unique characteristics of low voltage negative ion mass spectrometry will be applied to the sequencing of peptides and to the negative ionization of electron-impact sensitive bioorganic molecules. Included will be extensive efforts to find negative ion sensitizing groups. Studies leading to the enhancement of negative ion sensitivity will be carried out utilizing specific low-voltage (less than ev) resonance capture maxima obtained from negative ionization efficiency curves of these groups. The application of this technique to the analysis of mixtures will also be investigated.